Pressure measuring device



NW0 6 1945. w. v. HQBBS PRESSURE MEASURING DEVICE Filed May 15, 1944Patent d Nov. '6, .1945

PRESSURE MEASURING DEVICE Walter V. Hobbs, Columbus,,0hio, assignor toBanco Incorporated, Columbus, Ohio, a'corporation of Ohio ApplicationMay 15, 1844, Serial No. 535,655

7 Claims.

This invention relates to measuring apparatus and is particularlydirected to instruments for measuring pressure in the determination ofaltitudes, depths oi liquids and similar conditions.

An object of this invention is to provide an instrument for measuringpressure and indicating that pressure atla remote location.

Another object is to provide an instrumentfo measuring pressure andtransmitting the measurements to another location electrically so thatit will merely be necessary to extend one or more wires from the pointwhere the measuring operations are performed to the point where'theindications are recorded or read.

Another object of the invention is to provide a measuring deviceembodying a cell which is responsive to the pressures to be measured andto ge means adJacent the cell to tend to maintain the cell in apredetermined condition in opposition to potential changes causedbypressure variations, the cell also having associated with it suitablemeans responsive to the force necessary to maintain the condition totransmit indications to an indicator located remotely from the cell.

Another object is to provide a measuring device having a hermeticallysealed expansible cell con taininga gas or vapor which is ail'ected bytemperature changes and locating a heat exchange element adjacent thecell, movement of the cell in response to volumetric changes due totemperature variations caused by theoperations oi the scription,reference being had to the accompanylngdrawing wherein a preferred formof embodiment of the invention is clearly shown.

In the drawing:

The figure is a" diagrammatic view of a pressur measuring instrumentembodying the features the present invention.

In carrying out this invention, it is proposed to provide a cell whichmay be formed 01' any suitable material and is provided withasubstantially rigid section 2| including an end wall 22 and side walls23. Preferably, the side walls 21 are portions oi a cylinder 1'orconvenience in manufacture of the cell. At one end, the side wall issecured to the end wall 22 and at the other end has a movable wallsection 24 secured thereto. In the present instance, the movable iv'allsection is formed to include a bellows 25 which'may expand and contractin response to variationsin internal or external pressure. The bellows2! is so secured tov the side wall that a hermetic seal results whichwill retain a gas or vapor within the cell, the gas or vapor beingexpan'sible in response to increases in temperature. 1

thereto from which a resilient arm 21 projects ,toward the center 01'the cell 20. This arm carries a contact 28 at its outer end whichcontact is enheat'exchanger serving to control the supply of anoperating medium tothe heat exchange ele-' cell with a stationary walland a wall which is movable in response to the expansion and contractionof a gas or vapor within the cell, cooperating contacts being actuatedby the movable wall to control the supply of current to a resistanceheater employed toexpand' the vapor within the cell, the amount of heatnecessary to elect such expansion being measured to show the magnitudeof the force tending to resist such expansion.

Further objects and advantages 0! the present invention will be apparentfrom the following degaged when the cell is subject to normalconditions, by a similar-contact 29 carried at the free end of a-flngerIII projecting from the end wall 25A of the bellows 25. The contacts 20and 20 are arranged in an electric circuit 1| which includes aresistance heater 32 and a source of electrical energy such as thebattery 33. when the contacts are engaged, as illustrated inthe'drawing, and the main switch 34 is closed, the circuit '3! iscompleted and current will flow from the battery to the resistanceheater causing it to generate heat. This heat will be transmitted to thecell 2| due to the close proximity of the heater 32 thereto, causing thegas or vapor in the cell 28 to expand. When suiilcient expansion hasoccurred, the bellows 25 will. be extended causing the finger 30 andcontact 29 to move away from the contact 2!. When these contacts 2| and29 separate, the circuit 3| will be broken and the heater 32 will ceaseto operate. The gas-will then cool and contract causing the bellows 25to collapse and move the finger 3| and contact 2! toward contact 22.

on the-mess element 36.

event the cell it is exposedto a comp fierce, either through theapplication of or a mechanical force, the bellows 2E5 tenmto collapseand iorcc the inn-c; to is into the 01 section or the cell. "lheresiliency oi the 271 will pit this mov to avoid to the mecha. Since thecontacts will he in engagement,- however, the heater 82 y will he enerto deliver heat to the cell to caum the gas or vapor to w and counteractthe collapse of the hollows 26. As previously mentioned, when the intepressure is'sufilcient to extend the lcellows is until the contacts sepaante, the heater will he lie-energised to pet the vapor within the cellto cool. Due to this;

. essence between the it and sea of the lathe pres , and hollows meanshermetically joined thereto;

said cell} said a w s a source of current; movement of the movahlewallof 'said cell ca engagement and v disengagement of'said contact tocontrol the open ation of said has meant; and means for measup theperature within said cell. 3. sure measuring mecl.. 1... in combination,acell ha a stationary wall fluid me dispin said cell, said fluid beingexpansible under the influence or heat; a con tact carried by saidstationary wall; a complementalcontact mountedon said bellows means,

arrangement, the cell-will hunt a point of eduilihrium which isillustrated by the arrow the external pressure is hignmore heat will herequired within-the cell to cause the mediiun therein to exercisesumcienti'orce to counteract the external pressure. Thereforefhymeasuring the heat within the cell, the force tending to col: lapse thecell may he determined. To meamre the heat within the cellthe rigidsection is provlded with atemperature measuring element 239 such as athermocouple or platinum resistance element, the electricalcharacteristics or which are afiected when the elements are subjected tochanging temperatures. The temperature measuring element as is connectedby leads ill with i an indicator st ofany suitable type located at anydesired point relative to the cell. which indicator 83 will show theeflect of c 411:1: temperatures It desired the indicator 88 may becalibrated in pressure units to show directly the external pressuresapplied to the Eli. It will be seen that as the external pressuresincrease; the internal perature must also be increased to maintain theconstant distence between the end walls of the cell. it is proposed tooperate the instrument at a suff flciently high temperature that it willcool rapidly when the heate'rlll is de-ener.

From the foregoing, it i will "be apparent that since the only impulsestransmitted from the cell 253 to the indicator 38 are electricalimpulses, it will be unnece to have any connections other than wiresextending between these elements.

I e measuring instrument is, therefore, highly suitable for use inaircraft or in other locations where weight, and space are at a,premium.

e the form of-embodimentoi the present invention as hereindisclosed'constitutes a pre ierred form, it is to be understood thatother forms might be adopted, all 1-; within the scope of the claimswhich follow: p

I claim: p

1. Pressure measuring mechanism comprising in combination, a sealed cellhaving a stationary and a movable wall; coacting" means carried by saidwalls; means for heating said cell, controlled k by said'coactingmeans;and means for measur ing the temperature within said cell.

'2. ssure measuring mechanism comprising in combination-a sealed cellhaving a stationary and a movable wall; coasting contact means carriedby said walls; resistance means for has.

all

said contact ensa and'separating in response to movement of saidhollows; electrical heating means adjacent smd cell, said heating meanshaving s circuit inclu s a source of electrical energy and saidcontacts; and means ior measuring the temperature with n said cell.-

4. Pressure mechanism comprising in combination, a cell having astationary wall.

and bellows means hermeticaw joined thereto; fluid means disd in saidcell, said fiuid being enpansible under the influence of heat; a contactcarried by said stationary wall; a complemented contact mounted on saidbellows means, said contact engaging and separating in responsetomovement of said bellows; electrical heating means adjacent said cellsaid heating means having a circuit including a source ofclectrlcal'energy and said contacts; means in said cell. afiected bytemperature changes therein; and means disposed remotely from said cellfor measuring the eilect of the temperature changes on said means withinsaid cell.

5. Pressure measuring mechanism comprising in combination, a cell havinga stationary wall and bellows means hermetically joined thereto; fluidmeans disposed in .Lsaid cell, said fluid being ,emanslble under theinfluence of heat; a contact carried by said stationary wall; a comp1e=mental contact mounted on said bellowsfrneans,

- smd contact e gdsing and separating in response to movement of saidbellows; electrical heating means adjacent said cell, said heating meanshaving a circuit including a source or electrical energy and saidcontacts; means in said cell for generating an electriccurrent inresponse to tem- 0 nected with said current generating means forperature changes in said colt-and means con-= measuring the currentgenerated thereby.

6. Pressure measuring apparatus comprising, in combination, anexpansible cell: means for.

varying the temperature within said cell to tend to change a dimensionthereof; means responsive to thechange in dimension of said cell forcontrolling said temperature -va :1v means; and s m for measuring thetemperature within said cell.

7. Pressure measuring apparatus comprising,

in combination, an expansible cell; means for varying the temperaturewithin said cell to cause a portion thereof to move; means responsive tothe movement of said cell to control the operation of said temperaturevarying means; and means for indicating the temperature within saidcell'at a remote location having a circuit comprising

